Overriding impact proximity fuze

ABSTRACT

1. A fuze for effecting destruction of a target by igniting an explosive vehicle comprising means for radiating an electromagnet wave and for intercepting a target reflected portion thereof, first circuit means for generating said electromagnetic wave and for developing an output signal having a frequency correlative to the frequency difference between the radiated and reflected waves, said first circuit means being responsive to said radiating and intercepting means, second circuit means connected to said first circuit means to produce a variable potential signal indicative of the frequency of said output signal, electrostatically actuated means coupled to said second circuit means for selectively rendering said second circuit means nonresponsive to said output signal, and means for alternatively effecting ignition of the explosive vehicle by said potential signal or by target impact of the explosive vehicle, said last named means being responsive to said second circuit means.

atent [1 1 OVERRIDING IMPACT PROXIMI'IY lFIJZlE Robert M. Powell, Saratoga, Calif.

[73] Assignee: The United States oi America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Feb. 4, 1958 [21] Appl. No.: 713,274

[75] Inventor:

OTHER PUBLICATIONS Proximity Fuzes for Artillery by Haines Selvidge, Electronics Magazine, February 1946, Pages 104-109 are pertinent, Copy in division 10. classified [111 3,77,531 1 .luly 24, 1973 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Thomas l'l. Webb Attorney-Q. B. Warner and Q. E. Hodges EXEMPLARY CLAlM l. A fuze for effecting destruction ofa target by igniting an explosive vehicle comprising means for radiating an electromagnet wave and for intercepting a target reflected portion thereof, first circuit means for generating said electromagnetic wave and for developing an output signal having a frequency correlative to the frequency difference between the radiated and reflected waves, said first circuit means being responsive to said radiating and intercepting means, second circuit means connected to said first circuit means to produce a variable potential signal indicative of the frequency of said output signal, electrostatically actuated means coupled to said second circuit means for selectively rendering said second circuit means non-responsive to said output signal, and means for alternatively effecting igni tion of the explosive vehicle by said potential signal or by target impact of the explosive vehicle, said last named means being responsive to said second circuit means.

5 Claims, 2 Drawing Figures PATENFED Jul 24 INVENTOR. ROBERT M. IPOWELL ATTYS.

1 OVERRTDTNG IMPACT PRGXIMITY FUZE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally to a proximity fuze for an ordnance vehicle such, for example, as an antiaircraft projectile, and more particularly to a proximity fuze incorporating circuitry for providing target impact detonation of the projectile when on a target collision course.

Although numerous proximity fuzes having divers circuit configurations and operational characteristics have been heretofore devised and utilized in military ordnance applications, the majority of the present day radio proximity fuzes have only provided for projectile detonation by the fuze at a predetermined distance from the target whether the projectile was on a target collision course or on a non-collision course. It will be readily appreciated by those skilled in the ordnance art that notwithstanding the damaging and destructive effectiveness of a projectile detonated at a proximate distance from a target, considerably greater kill probability is inherently obtainable from a direct hit upon the target by the projectile.

Accordingly, a principle object of the present invention is to provide a new and improved proximity fuze having dual initiating operational characteristics.

Another object of this invention is to provide a new and improved radio proximity fuze for a projectile selectively responsive to the position of a target relative to the path of the projectile.

Still another object of the instant invention is the provision of electrostatic circuit means within a projectile proximity fuze for deactivating the proximity response of the fuze when the projectile is on a target collision course.

A further object of the present invention is to provide a proximity fuze for an airborne ordnance vehicle having an overriding impact operational characteristic.

A still further object of this invention is to provide a new and improved fuze for a projectile alternatively responsive to the proximate distance to and electrostatic effect of an aerial target.

Another still further object of this invention is the provision of new and improved circuit means with a projectile proximity fuze for selectively effecting target impact detonation of the projectile.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an overall circuit diagram of the proximity fuze system according to the present invention; and,

FIG. 2 is a pictorial view illustrating the divers operational characteristics of the proximity fuze of FIG. 1.

Referring now to the drawing wherein like reference characters designate similar or identical parts throughout the several views and more particularly to FIG. 1 whereon a proximity fuze, generally indicated by the reference numeral 11, according to the instant invention is shown as including conventional proximity fuze componential circuit stages of an antenna 12, an oscillator detector 13, an audio band pass amplifier 14, and a firing circuit 15, which includes an electroresponsive primer 16. The oscillator-detector circuit 13 generates a suitable electromagnetic wave signal which is radiated into space by the antenna 12. The antenna, which includes the conductive casing of the projectile 17 within which the proximity fuze 11 is mounted, develops a forwardly directed lobe radiation pattern 18 as shown in FIG. 2 of the drawing. The presence of a suitable target, such for example as an aircraft 19 within the radiation pattern 18 will cause a reflection ofa portion of the radiated electromagnetic energy wave back to the antenna 12 whereupon a ripple, or audio, frequency signal is developed in the oscillator-detector circuit 13. This relatively low frequency ripple signal may be regarded as a beat frequency signal existing between the frequency of the transmitted signal and the shifted frequency of the reflected signal due to the doppler effect resulting from the relative movement between the projectile 17 and target 19. The ripple signal is fed to the tuned audio amplifier 14. When the frequency of the ripple signal approaches the center frequency of the band pass of the audio amplifier stage '14, which center frequency is preselected to correspond to a ripple frequency signal indicative of a lethal distance of the projectile from the target, a triggering signal is applied to the thyratron 21 of the firing circuit 15. The thyratron is rendered conductive whereupon the energy in a charged condenser 22 is discharged through the thyratron 21 and primer 16 thereby igniting the primer and detonating the main explosive charge 23 of the projectile 17 within a proximate distance from the target 19.

Although the aforedescribed mode of proximity fuze operation results in target destruction in many military applications, under certain target conditions, such for example as in the case of an extremely fast and small target, only nominal damage may be inflicted upon the target without consequent destruction thereof. Under these target conditions if a direct hit were realizable, such for example as would occur if the projectile were on a target collision course, the target would be completely destroyed upon impact of the projectile therewith instead of merely being damaged by a proximate projectile burst. Accordingly, the instant invention pro vides a target sensing circuit, generally indicated by reference numeral 24, for momentarily paralyzing a portion of the proximity fuze 11 when the projectile 17 is on a collision path 25 as shown on FIG. 2 with the aerial target 19 thereby to allow for a direct hit.

As shown on FIG. 1, the sensing, or control, circuit 24 includes a metallic annular member 26 positioned in the nose portion of projectile 17 and substantially completely insulated from the antenna 12 and projectile casing. The conductive member 26 is electrically coupled to the grid electrode of an electrometer tube 27. The anode of the tube 27 is coupled to a suitable potential energy source B+ through a serially connected inductance 28 and resistor 29, while the cathode of the tube is electrically coupled through an inductance 31 to the forward end 32 of the projectile. A by-pass capacitor 33 interconnects the common junction point 34 between inductance 28 and resistor 29 to the forward end portion 32 of the projectile. A conductor 35 electrically connects the junction point 34 of the control circuit 24 to the control grid of the second electron tube 36 in the tuned amplifier circuit stage 14. A blocking capacitor 37 is provided within this connecting circuit for preventing impression of the B+ potential upon the control grid of tube 36.

If the conductive ring 26 is charged negatively relative to the forward portion 32 of the projectile casing upon firing ofthe projectile 17, an electrostatic field pattern, designated by the dashed lines 38, will exist between the ring member 26 and the forward portion 32 of the casing. It is to be understood that the negative charge applied to the member 26 in any well known manner is of sufficient magnitude to maintain the electrometer tube 27 normally non-conducting. If the projectile 17 is of a non-collision course 39 with the target 19, no distortion in the pattern of the electrical lines of force will occur and the negative charge on the annular member 26 will be retained thereby maintaining the electrometer tube cut-off. Under this condition, detonation of the main charge 23 of the projectile 17 will be effected by conventional proximity fuze action. In the event, however, that the projectile 17 is on a target collision course 25, proximity of the target will cause an increasingly larger distortion in the electric field pattern 38 with a consequent relatively minute reduction, or leakage, of the negative charge upon annular member 26. The inherent extreme sensitivity of an electrometer tube to any reduction in the potential charge upon the control grid thereof will render the electrometer tube 27 conductive whereupon a negative potential signal will be applied through conductor 35 to the control grid of amplifier tube 36 in stage 14 of sufficient magnitude to render it cut-off. Consequently, the ripple frequency signal developed in the oscillator-detector stage 13 indicative of a lethal projectile distance to the target will not result in the generation of a triggering signal for rendering thyratron 21 conductive and primer 16 ignited by discharge therethrough of charged condenser 22. Instead target impact will result and the primer l6 ignited by the discharge of condenser 22 through a conventional impact responsive switch 41.

In the event that the target should avoid a direct hit by the projectile, the original electric field pattern will be restored to its initial configuration upon the projectile passing by the target. Restoration of the electric field pattern 38 will restore the initial negative charge upon the annular member 26 whereupon the electrometer tube 27 will be cut-off and amplifier tube 36 again rendered responsive to the ripple signal output of the oscillator-detector circuit 13. It is to be understood that the intensity of the electrostatic field is preselected to be of sufficient magnitude to detect the presence of a target prior to the developing of the triggering signal by the amplifier stage 14 of the proximity fuze 11.

In summary, the hereinbefore disclosed circuit illustrates the development of a radio proximity fuze having an electrostatic control circuit associated therewith for providing for target collision under certain operational conditions.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A fuze for effecting destruction of a target by igniting an explosive vehicle comprising means for radiating an electromagnetic wave and for intercepting a target reflected portion thereof, first circuit means for generating said electromagnetic wave and for developing an output signal having a frequency correlative to the frequency difference between the radiated and reflected waves, said first circuit means being responsive to said radiating and intercepting means, second circuit means connected to said first circuit means to produce a variable potential signal indicative of the frequency of said output signal, electrostatically actuated means coupled to said second circuit means for selectively rendering said second circuit means non-responsive to said output signal, and means for alternatively effecting ignition of the explosive vehicle by said potential signal or by target impact of the explosive vehicle, said last named means being responsive to said second circuit means.

2. A fuze for effecting destruction of a target by igniting an explosive vehicle comprising an oscillator for generating an electromagnetic wave signal, an antenna coupled to said oscillator for radiating said signal and for receiving a target reflected portion thereof, a detector coupled to said oscillator for developing an output signal having an instantaneous frequency correlative to the difference between the radiated and reflected signals, an amplifier coupled to said oscillator and detector for developing a triggering signal in response to an output signal of a predetermined instantaneous frequency, electrostatically actuated circuit means coupled to said amplifier for selectively rendering said amplifier non-responsive to said output signal, impact responsive means and circuit means for alternatively effecting ignition of the explosive vehicle by said triggering signal or said impact responsive means, said last named circuit means being coupled to said amplifier.

3. A fuze for effecting destruction of a target by detonation of a projectile comprising antenna means for radiating an electromagnetic wave signal and for intercepting a target reflected portion thereof, first circuit means connected to said antenna means for generating said signal and for developing an output signal of a frequency proportional to the frequency difference between the generated and reflected signals, tuned circuit means connected to said first circuit means to produce a variable potential signal, said potential signal being indicative of the frequency of said output signal, electrostatically actuated circuit means including an electrometer for selectively developing a potential signal to render said tuned circuit means non-responsive to said output signal, normally ineffective firing circuit means for detonating the projectile upon being rendered effective by said variable potential signal, and means for rendering said firing circuit means effective upon target impact of the projectile, said last named means connected to said tuned circuit means.

4. A fuze for effecting demolition of a target by detonation of a projectile comprising antenna means for radiating an electromagnetic wave signal and for intercepting a target relfected portion thereof, first circuit means connected to said antenna means for generating said signal and for developing a first output signal of a frequency corresponding to the frequency difference between the generated and reflected signals, selective amplifer means connected to said first circuit means for producing a triggering signal in response to a predetermined frequency of the first output signal, firing circuit means for effecting detonation of the projectile in response to said triggering signal applied thereto, means for producing an electrostatic field, an electrometer 3 ,747 ,5 3 1 5 6 tube operatively coupled to said last recited means and 5. A fuze according to claim 4 wherein said means for to said amplifier means for developing a second output producing an electrostatic field includes a negatively signal in response to distortion of said electrostatic field charged conductor member insulatingly mounted on for rendering said selective amplifier circuit means the casing of the projectile. non-responsive to said first output signal. 5 

1. A fuze for effecting destruction of a target by igniting an explosive vehicle comprising means for radiating an electromagnetic wave and for intercepting a target reflected portion thereof, first circuit means for generating said electromagnetic wave and for developing an output signal having a frequency correlative to the frequency difference between the radiated and reflected waves, said first circuit means being responsive to said radiating and intercepting means, second circuit means connected to said first circuit means to produce a variable potential signal indicative of the frequency of said output signal, electrostatically actuated means coupled to said second circuit means for selectively rendering said second circuit means non-responsive to said output signal, and means for alternatively effecting ignition of the explosive vehicle by said potential signal or by target impact of the explosive vehicle, said last named means being responsive to said second circuit means.
 2. A fuze for effecting destruction of a target by igniting an explosive vehicle comprising an oscillator for generating an electromagnetic wave signal, an antenna coupled to said oscillator for radiating said signal and for receiving a target reflected portion thereof, a detector coupled to said oscillator for developing an output signal having an instantaneous frequency correlative to the difference between the radiated and reflected signals, an amplifier coupled to said oscillator and detector for developing a triggering signal in response to an output signal of a predetermined instantaneous frequency, electrostatically actuated circuit means coupled to said amplifier for selectively rendering said amplifier non-responsive to said output signal, impact responsive means and circuit means for alternatively effecting ignition of the explosive vehicle by said triggering signal or said impact responsive means, said last named circuit means being coupled to said amplifier.
 3. A fuze for effecting destruction of a target by detonation of a projectile comprising antenna means for radiating an electromagnetic wave signal and for intercepting a target reflected portion thereof, first circuit means connected to said antenna means for generating said signal and for developing an output signal of a frequency proportional to the frequency difference between the generated and reflected signals, tuned circuit means connected to said first circuit means to produce a variable potential signal, said potential signal being indicative of the frequency of said output signal, electrostatically actuated circuit means including an electrometer for selectively developing a potential signal to render said tuned circuit means non-responsive to said output signal, normally ineffective firing circuit means for detonating the projectile upon being rendered effective by said variable potential signal, and means for rendering said firing circuit means effective upon target impact of the projectile, said last named means connected to said tuned circuit means.
 4. A fuze for effecting demolition of a target by detonation of a projectile comprising antenna means for radiating an electromagnetic wave signal and for intercepting a target relfected portion thereof, first circuit means connected to said antenna means for generating said signal and for developing a first output signal of a frequency corresponding to the frequency difference between the generated and reflected signals, selective amplifer means connected to said first circuit means for producing a triggering signal in response to a predetermined frequency of the first output signal, firing circuit means for effecting detonation of the projectile in response to said triggering signal applied thereto, means for producing an electrostatic field, an electrometer tube operatively coupled to said last recited means and to said amplifier means for developing a second output signal in response to distortion of said electrostatic field for rendering said selective amplifier circuit means Non-responsive to said first output signal.
 5. A fuze according to claim 4 wherein said means for producing an electrostatic field includes a negatively charged conductor member insulatingly mounted on the casing of the projectile. 